Preparation

Position a rack in the center of the oven and heat to 400°F.

Coarsely crush the dried chiles, cumin, coriander, and peppercorns in a mortar and pestle. Add the garlic and a good pinch of salt and pound. Add 2 Tbs. of the oil and continue to pound to make a paste.

Put the potatoes in a large (6- to 8-quart) pot with enough cool water to cover by at least 1 inch. Add 2 tsp. salt, and bring to a boil. Cook until tender but still holding their shape, 10 to 15 minutes. Drain in a colander, and then shake the colander to rough them up; the resulting irregular edges will get nice and crisp in the oven.

Transfer the potatoes to a large roasting pan and drizzle with the remaining 3 Tbs. oil. Add the spice paste and gently toss to coat. Roast until golden brown and crisp, adding a little more oil if the pan looks dry, 45 to 55 minutes. Season to taste with salt and serve.